1. Field of the Invention
The present invention relates in general to an electronic component mounting apparatus and in particular to such an apparatus which has different sorts of mounting heads for mounting different sorts of electronic components on a substrate such as a printed wiring board.
2. Related Art Statement
There has conventionally been known an electronic component mounting apparatus for mounting, on a printed wiring board, different sorts of electronic components that differ from each other with respect to size, shape, weight, etc. Generally, the apparatus has different sorts of mounting heads which have different sizes or constructions corresponding to different sorts of electronic components. Japanese Utility Model Application laid-open under Publication No. 59-95700 discloses an apparatus of the above indicated type. The disclosed apparatus has a table and different sorts of mounting heads supported by the table. The different sorts of mounting heads selectively are used for mounting corresponding sorts of electronic components. More specifically described, the table is rotatable about an axis, and the mounting heads of the different sorts are supported by the table such that all of them are equiangularly distant from each other on a circle whose center is located on the rotation axis of the table, and that they consist of a plurality of pairs of mounting heads each of which pairs consist of two mounting heads of the same sort which are diametrically opposite to each other with respect to the rotation axis of the table. The table is rotated intermittently about the rotation axis thereof by a drive device in such a manner that the table is rotated, for each of the intermittent rotations thereof, by an intermittent rotation amount equal to the above indicated, equiangular distance. Consequently, the two, same mounting heads of each of the pairs are stopped, in order, at an electronic component receive or take place and an electronic component release or mount place, respectively, which places are diametrically opposite to each other with respect to the rotation axis of the table, whereby one of the two mounting heads takes an electronic component at the take place and the other mounts an electronic component on a printed wiring board at the mount place.
However, the above identified mounting apparatus is not capable of intermittently rotating the table by an intermittent rotation amount different from the rotation amount equal to the above indicated equiangular distance. Consequently, all the mounting heads of the different sorts are stopped at the operation places, i.e. electronic component take and mount places, regardless of which sort of mounting heads are used currently for the electronic component taking and mounting operation. Thus, the prior art apparatus needs a comparatively long time for moving the mounting heads, of the sort which currently are used, to the operation places. In other words, the prior art apparatus has the problem that the mounting efficiency is low.